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  Light-emitting component provided with a luminescence conversion elementUSPTO Application #: 20070018102Title: Light-emitting component provided with a luminescence conversion element Abstract: The invention encompasses a light-emitting component having at least one primary radiation source that in operation emits an electromagnetic primary radiation, and at least one luminescence conversion element by means of which at least a portion of the primary radiation is converted into a radiation of altered wavelength. Disposed after the luminescence conversion element in a radiation direction of the component is a filter element comprising a plurality of nanoparticles, said nanoparticles comprising a filter substance which by absorption selectively reduces the radiation intensity of at least one spectral subregion of an unwanted radiation. (end of abstract)
Agent: Fish & Richardson PC - Minneapolis, MN, US Inventors: Bert Braune, Gunter Waitl USPTO Applicaton #: 20070018102 - Class: 250336100 (USPTO) Related Patent Categories: Radiant Energy, Invisible Radiant Energy Responsive Electric Signalling The Patent Description & Claims data below is from USPTO Patent Application 20070018102. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This patent application claims the priority of European Patent Application 03015972.7 and German Patent Application 10361661.6, whose disclosure content is incorporated herein by reference. [0002] The invention concerns a light-emitting component comprising at least one primary radiation source that in operation emits a primary electromagnetic radiation, and at least one luminescence conversion element by means of which at least a portion of the primary radiation is converted into a radiation of altered wavelength. [0003] Such a component is described for example in DE 101 33 352 A1. Serving as the primary radiation source is at least one luminescent diode that emits a primary radiation in the range of 300 to 485 nm, said primary radiation being partially or completely converted into longer-wave radiation by phosphors. Components in which a primary radiation in the UV or near-UV region is converted into visible light are particularly well suited for generating white light with high color rendering by means of various phosphor materials. [0004] A disadvantage of such components can be that they exhibit non-negligible residual emission of primary radiation in the UV or near-UV region of the spectrum. This can be the case in particular when high-power luminescent diodes are used as the primary radiation source. Such residual emission is to be avoided insofar as possible, since electromagnetic radiation in the UV or the near-visible-UV wavelength range can with intense exposure have a damaging effect on the human eye. Radiation in the UV or violet region (400-420 nm) can injure the eye, depending on the radiant power striking it. At wavelengths below 400 nm the main problem is cataract formation, i.e., clouding of the ocular lens. At wavelengths between 400 nm and 420 nm, photochemical degradation of the retina may also occur. [0005] An object of the present invention is to specify a light-emitting component comprising means for at least partially reducing the radiation intensity of an unwanted radiation. [0006] This object is achieved by means of a component according to Claim 1. Preferred improvements and advantageous configurations of the invention are the subject matter of the dependent claims. [0007] According to the invention, in a component of the species recited at the beginning hereof, disposed after the luminescence conversion element in a radiation direction of the component is a filter element comprising a plurality of nanoparticles. The nanoparticles comprise a filter substance which by absorption selectively reduces the radiation intensity of at least one spectral range of an unwanted radiation. [0008] "Nanoparticles" in connection with the invention are to be understood as particles having an average particle diameter greater than or equal to 0.1 nm and less than or equal to 100 nm. [0009] The extent of a nanoparticle is relatively small compared to a wavelength of visible radiation. As a result, visible radiation is substantially not scattered inelastically from nanoparticles, but rather a Rayleigh scattering occurs by which the visible radiation is scattered with almost no loss of energy. Hence, the filter element reduces the radiation intensity of substantially only the wavelength range of an electromagnetic radiation generated in the component for which the filter substance is absorptive. The radiation intensity of at least a portion of the unwanted radiation can be reduced selectively in this way. [0010] The term "unwanted radiation" does not imply in relation to the invention that this radiation is absolutely unwanted, but rather that emission of this radiation from the component is unwanted and is therefore to be avoided insofar as possible. [0011] In an advantageous embodiment of the component, the unwanted radiation is the primary radiation or a spectral subregion of the primary radiation. [0012] The unwanted radiation preferably is from or overlaps with a wavelength range of less than or equal to 420 nm and greater than or equal to 10 nm. [0013] In a further embodiment of the component, the primary radiation source preferably comprises at least one luminescent diode that in operation emits UV radiation and/or blue light. The radiation intensity of the spectral subregion of the unwanted radiation is preferably reduced by least 50%. [0014] To prevent insofar as possible any inelastic scattering of unwanted radiation from the nanoparticles, the nanoparticles advantageously have a d.sub.50 value which, measured in Q.sub.0, is smaller than or equal to 25 nm, preferably smaller than or equal to 21 nm and greater than or equal to 1 nm. [0015] Particularly preferably, the nanoparticles have a d.sub.50 value which, measured in Q.sub.0, is smaller than or equal to 1/20 of a minimum wavelength of the unwanted radiation and greater than or equal to 1 nm. In a particularly advantageous embodiment hereof, all the nanoparticles have an average diameter that is no more than 1/20.sup.th of a minimum wavelength of the unwanted radiation. [0016] A preferred embodiment provides that the filter substance contains at least one material from the group consisting of the metal oxide group of materials, the sulfide group of materials, the nitride group of materials and the silicate group of materials. It is also possible in terms of the invention for the filter element to comprise plural subsets of nanoparticles having different filter substances. In such a case, only the filter substance of at least one of the subsets of nanoparticles need satisfy the conditions of the invention or of its embodiments. [0017] The filter substance particularly preferably comprises at least one material from the group consisting of titanium dioxide, cerium dioxide, zirconium dioxide, zinc oxide, tungsten oxide, zinc sulfide and gallium nitride. [0018] The nanoparticles are advantageously embedded in a matrix material that preferably is insensitive to UV radiation. To this end, the matrix material advantageously comprises at least one material from the group consisting of silicone, spin-on-glasses, silicon compounds and polymers. [0019] To achieve the least possible sedimentation of nanoparticles in the matrix material, the nanoparticles are provided to particular advantage with a dispersion-enhancing surface coating or surface modification that improves their dispersibility in the matrix material. [0020] Further features, advantages and suitabilities of the invention will emerge from the exemplary embodiment described hereinafter in connection with FIGS. 1 to 2b. Therein: [0021] FIG. 1 is a schematic sectional view of an exemplary embodiment of the component, [0022] FIG. 2a is a calculated transmission spectrum of a filter element comprising microparticles, and [0023] FIG. 2b is a calculated transmission spectrum of an exemplary embodiment of a filter element according to the invention. [0024] In the exemplary embodiments and figures, like or like-acting constituents are provided with the same respective reference numerals. The illustrated elements in the figures should not be considered true to scale. Rather, they may in part be depicted as over-large to provide a better understanding. Continue reading... Full patent description for Light-emitting component provided with a luminescence conversion element Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Light-emitting component provided with a luminescence conversion element patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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